U.S. patent application number 15/502938 was filed with the patent office on 2017-08-10 for pump device.
This patent application is currently assigned to KYB Corporation. The applicant listed for this patent is KYB Corporation. Invention is credited to Koichiro AKATSUKA, Tomoyuki FUJITA, Hiroki GOMI, Fumiyasu KATOU, Tomoyuki NAKAGAWA.
Application Number | 20170227007 15/502938 |
Document ID | / |
Family ID | 55399657 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170227007 |
Kind Code |
A1 |
AKATSUKA; Koichiro ; et
al. |
August 10, 2017 |
PUMP DEVICE
Abstract
A pump device includes a flow control valve that returns a part
of working fluid discharged from a pump to the suction side, and
the flow control valve includes a valve body, a first fluid
pressure chamber that is provided so as to face against a
first-side end surface of the valve body and that is communicated
with a discharge channel, a second fluid pressure chamber that is
provided so as to face against a second-side end surface of the
valve body and that is communicated with the discharge channel, a
biasing member that is accommodated in the second fluid pressure
chamber for biasing the valve body in the valve-closing direction,
and a pressure regulator that is provided in a communicating
passage through which the discharge channel is communicated with
the second fluid pressure chamber and that adjusts pressure in the
second fluid pressure chamber.
Inventors: |
AKATSUKA; Koichiro; (Gifu,
JP) ; FUJITA; Tomoyuki; (Gifu, JP) ; NAKAGAWA;
Tomoyuki; (Gifu, JP) ; KATOU; Fumiyasu;
(Aichi, JP) ; GOMI; Hiroki; (Gifu, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYB Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
KYB Corporation
Tokyo
JP
|
Family ID: |
55399657 |
Appl. No.: |
15/502938 |
Filed: |
August 24, 2015 |
PCT Filed: |
August 24, 2015 |
PCT NO: |
PCT/JP2015/073709 |
371 Date: |
February 9, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2/3446 20130101;
F04C 15/064 20130101; F04C 14/08 20130101; F04C 2/344 20130101;
F04C 14/26 20130101; F04C 2270/185 20130101; F04C 14/24 20130101;
F01C 21/0863 20130101 |
International
Class: |
F04C 14/26 20060101
F04C014/26; F04C 15/06 20060101 F04C015/06; F04C 2/344 20060101
F04C002/344 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2014 |
JP |
2014-175449 |
Claims
1. A pump device for supplying working fluid to a fluid pressure
apparatus comprising: a pump configured to discharge the working
fluid into a discharge channel by sucking and pressurizing the
working fluid; and a flow control valve configured to return a part
of the working fluid discharged from the pump to a suction side;
wherein the flow control valve comprises: a valve body; a first
fluid pressure chamber provided so as to face against a first-side
end surface of the valve body, the first fluid pressure chamber
being communicated with the discharge channel; a second fluid
pressure chamber provided so as to face against a second-side end
surface of the valve body, the second fluid pressure chamber being
communicated with the discharge channel; a biasing member
accommodated in the second fluid pressure chamber in a compressed
state for biasing the valve body in a valve-closing direction; and
a pressure regulator provided in a communicating passage through
which the discharge channel is communicated with the second fluid
pressure chamber, the pressure regulator being configured to adjust
pressure in the second fluid pressure chamber.
2. The pump device according to claim 1, wherein the pressure
regulator further comprises: an orifice provided in the
communicating passage; and a relief valve provided in a relief
passage branched off from the communicating passage at a downstream
side of the orifice, the relief valve being capable of changing a
relief pressure.
3. The pump device according to claim 2, wherein the relief valve
further comprises a proportional solenoid that is capable of
changing the relief pressure.
4. The pump device according to claim 2, wherein the relief valve
is configured to change the relief pressure in accordance with a
rotation speed of the pump.
5. The pump device according to claim 2, wherein the relief valve
is configured to change the relief pressure in accordance with a
pressure required by the fluid pressure apparatus.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pump device.
BACKGROUND ART
[0002] In the related art, there are known pump devices, in which a
flow control valve is provided in order to keep a discharge flow
amount of the pump constant.
[0003] JP05-61482U describes a pump device in which a flow control
valve is provided at an intermediate position in a drain passage
that is connected between a suction passage and a discharge passage
of a vane pump. With the pump device described in JP05-61482U,
working oil discharged from pump chambers to the discharge passage
in a manner proportional to the rotation speed of the pump is
supplied to a hydraulic driving device through an orifice. In
addition, with the pump device described in JP05-61482U, the flow
control valve is controlled so as to be opened/closed such that the
amount of the working oil supplied from the vane pump to the
hydraulic driving device is controlled so as to be substantially
constant.
SUMMARY OF INVENTION
[0004] However, with the pump device in JP05-61482U, a restrictor
is provided in the discharge passage of the pump. Therefore, a
pressure loss is caused at the restrictor, and torque required for
driving the pump becomes correspondingly greater.
[0005] The present invention has been conceived in light of the
problems mentioned above, and an object thereof is to provide a
pump device capable of controlling a flow amount while reducing a
driving torque for a pump.
[0006] According to one aspect of the present invention, a pump
device that is configured to supply working fluid to a fluid
pressure apparatus includes: a pump that is configured to discharge
the working fluid into a discharge channel by sucking and
pressurizing the working fluid; and a flow control valve that is
configured to return a part of the working fluid discharged from
the pump to a suction side; wherein the flow control valve
comprises: a valve body; a first fluid pressure chamber that is
provided so as to face against a first-side end surface of the
valve body and that is communicated with the discharge channel; a
second fluid pressure chamber that is provided so as to face
against a second-side end surface of the valve body and that is
communicated with the discharge channel; a biasing member that is
accommodated in the second fluid pressure chamber in a compressed
state for biasing the valve body in a valve-closing direction; and
a pressure regulator that is provided in a communicating passage
through which the discharge channel is communicated with the second
fluid pressure chamber and that adjusts pressure in the second
fluid pressure chamber.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 is a hydraulic circuit diagram of a pump device
according to an embodiment of the present invention.
[0008] FIG. 2 is a map showing the relationship between the pump
rotation speed and the pressure in a second fluid pressure chamber
for the pump device at a certain target flow amount.
[0009] FIG. 3 is a map showing the relationship between the
pressure in the second fluid pressure chamber and the applied
current for a proportional solenoid.
[0010] FIG. 4 is a map showing the relationship between the
required pressure for the pump device and the pressure in the
second fluid pressure chamber.
[0011] DESCRIPTION OF EMBODIMENT
[0012] A pump device 100 according to an embodiment of the present
invention will be described below with reference to the
drawings.
[0013] FIG. 1 is a hydraulic circuit diagram of a pump device
100.
[0014] The pump device 100 includes a pump 1, in which working oil
serving as working fluid is sucked from a suction channel 81
connected to a tank 4 and in which the working oil is pressurized
and discharged to a discharge channel 82, and a flow control valve
2 that returns a part of the working oil discharged from the pump 1
to the suction channel 81 on the suction side and controls the flow
amount of the working oil supplied to a fluid pressure apparatus 50
from the pump 1.
[0015] The pump 1 is a fixed displacement vane pump. The pump 1
includes a rotor 11 that is rotationally driven by a driving
device, such as an engine (not shown), a plurality of vanes 12 that
are provided so as to be movable in a reciprocating manner in the
radial direction with respect to the rotor 11, and a cam ring 13 in
which the rotor 11 is accommodated and tip ends of the vanes 12 are
brought into sliding contact with a cam face 13a on the inner
circumference of the cam ring 13 by rotation of the rotor 11.
[0016] In the rotor 11, slits 14 having openings in an outer
circumferential surface are formed in a radiating pattern with
predetermined gaps. The vanes 12 are respectively inserted into the
slits 14 in a freely slidable manner.
[0017] At the base-end sides of the slits 14, back pressure
chambers 15 into which the discharge pressure of the pump 1 is
guided are defined. The adjacent back pressure chambers 15
communicate with each other through an arc-shaped groove 16 formed
in the rotor 11. The pump discharge pressure is constantly guided
to the groove 16. The vanes 12 are pushed into the directions in
which the vanes 12 project out from the slits 14 by the pressure in
the back pressure chambers 15 and the centrifugal force caused by
the rotation of the rotor 11, and thereby, the tip ends of the
vanes 12 are brought into contact with the cam face 13a on the
inner circumference of the cam ring 13. With such a configuration,
a plurality of pump chambers 17 are defined within the cam ring 13
by the outer circumferential surface of the rotor 11, the cam face
13a of the cam ring 13, and pairs of adjacent vanes 12.
[0018] The cam ring 13 is an annular member whose cam face 13a on
the inner circumference has a substantially oval shape, and the cam
ring 13 has suction regions 13b and 13d in which the volumes of the
pump chambers 17 are expanded as the rotor 11 is rotated and
discharge regions 13c and 13e in which the volumes of the pump
chambers 17 are contracted as the rotor 11 is rotated.
[0019] While the rotor 11 is fully rotated, the respective pump
chambers 17 suck the working oil from the suction channel 81
through a suction port (not shown) in the suction region 13b of the
cam ring 13, and discharge the sucked working oil to the discharge
channel 82 through a discharge port 18 in the discharge region 13c
of the cam ring 13. Subsequently, the respective pump chambers 17
suck the working oil from the suction channel 81 through the
suction port (not shown) in the suction region 13d of the cam ring
13, and discharge the sucked working oil to the discharge channel
82 through the discharge port 18 in the discharge region 13e of the
cam ring 13. As described above, the respective pump chambers 17
are expanded/contracted by the rotation of the rotor 11, and the
working oil is sucked/discharged twice while the rotor 11 is fully
rotated. The pump rotation speed N of the pump 1 changes in
accordance with the rotation speed of the driving device. As the
pump rotation speed N is increased, the discharge flow amount of
the pump 1 is increased in a manner proportional to the rotation
speed.
[0020] As long as the pump 1 is of a rotationally-operated fixed
displacement type, the pump 1 may be of any type, such as a gear
pump.
[0021] The flow control valve 2 includes a spool 21 serving as a
valve body inserted into a valve accommodating bore 25 in a freely
slidable manner, a first fluid pressure chamber 23 that is provided
so as to face against a first-side end surface of the spool 21, a
second fluid pressure chamber 24 that is provided so as to face
against a second-side end surface of the spool 21, and a return
spring 22 serving as a biasing member accommodated in the second
fluid pressure chamber 24 in a compressed state for biasing the
spool 21 in the valve-closing direction.
[0022] The spool 21 includes a first land part 21a and a second
land part 21b that slide along the inner circumferential surface of
the valve accommodating bore 25.
[0023] In the first fluid pressure chamber 23, a first stopper
portion 21c is arranged by being connected to the first land part
21a so as to be brought into contact with a bottom portion of the
valve accommodating bore 25 when the spool 21 is moved in the
direction in which the volume of the first fluid pressure chamber
23 is contracted and so as to restrict the movement of the spool 21
exceeding a predetermined amount.
[0024] A first communicating passage 83, which is branched off from
the discharge channel 82, is connected to the first fluid pressure
chamber 23 and a second communicating passage 84, which is branched
off from the discharge channel 82, is connected to the second fluid
pressure chamber 24. In addition, a drain passage 85, which is
communicated with or shut off from the first fluid pressure chamber
23 by the first land part 21a, is connected to the flow control
valve 2.
[0025] The spool 21 is stopped at a position where the load exerted
by the pressure of the working oil guided to the first fluid
pressure chamber 23 and the second fluid pressure chamber 24, which
are defined at both ends thereof, is balanced with the biasing
force exerted by the return spring 22.
[0026] When the total load of the load exerted by the pressure in
the second fluid pressure chamber 24 and the biasing force exerted
by the return spring 22 is greater than the load exerted by the
pressure in the first fluid pressure chamber 23, the return spring
22 is extended and the spool 21 is in a state in which the first
stopper portion 21c is in contact with the bottom portion of the
valve accommodating bore 25.
[0027] In this state, the first land part 21a of the spool 21 shuts
off the communication between the first fluid pressure chamber 23
and the drain passage 85. Thus, all of the working oil discharged
from the pump 1 is supplied to a the fluid pressure apparatus
50.
[0028] In contrast, when the load exerted by the pressure in the
first fluid pressure chamber 23 is greater than the total load of
the load exerted by the pressure in the second fluid pressure
chamber 24 and the biasing force exerted by the return spring 22,
the spool 21 is moved against the biasing force exerted by the
return spring 22.
[0029] In this state, the first land part 21a of the spool 21
allows communication between the first fluid pressure chamber 23
and the drain passage 85. Thus, a part of the working oil
discharged from the pump 1 is returned to the suction channel 81
through the first fluid pressure chamber 23 and the drain passage
85.
[0030] The flow control valve 2 further includes a pressure
regulator 3 that is provided in the second communicating passage 84
through which the discharge channel 82 is communicated with the
second fluid pressure chamber 24 and that adjusts the pressure in
the second fluid pressure chamber 24. The pressure regulator 3
includes an orifice 40 provided in the second communicating passage
84, a relief passage 86 that is branched off from the second
communicating passage 84 at the downstream side of the orifice 40
and that communicates with the tank 4, and a relief valve 30
provided in the relief passage 86.
[0031] The relief valve 30 includes a spring 31 that exerts the
biasing force in the valve-closing direction, a proportional
solenoid 32 that exerts the biasing force in the valve-closing
direction so as to be capable of changing the relief pressure Pr,
and a pilot passage 33 through which the pressure in the relief
passage 86 acts in the valve-opening direction.
[0032] The pressure P2 in the second fluid pressure chamber 24,
which is pressure at the downstream side of the orifice 40, acts on
the relief valve 30 through the relief passage 86 and the pilot
passage 33 so as to exert the biasing force in the valve-opening
direction.
[0033] When the pressure P2 in the second fluid pressure chamber 24
is greater than the relief pressure Pr that is determined by the
total of the biasing force exerted by the spring 31 and the biasing
force exerted by the proportional solenoid 32, the relief valve 30
is opened and the working oil in the second fluid pressure chamber
24 is discharged through the second communicating passage 84 to the
tank 4. When the pressure P2 in the second fluid pressure chamber
24 is equal to the relief pressure Pr, the relief valve 30 is
closed. In this way, the pressure P2 in the second fluid pressure
chamber 24 is adjusted by the relief valve 30 so as to be equalized
to the relief pressure Pr. It suffices that the total biasing force
exerted by the proportional solenoid 32 and the spring 31 be in the
valve-closing direction, and either the proportional solenoid 32 or
the spring 31 may exert the biasing force in the valve-opening
direction.
[0034] A controller 60 controls the applied current I applied to
the proportional solenoid 32. In addition, the pump rotation speed
N of the pump 1 detected by a pump-rotation-speed detector 70 and
the signal for the pressure required by the fluid pressure
apparatus 50 are input to the controller 60. The signal for the
pressure required by the fluid pressure apparatus 50 will be
described later.
[0035] A map (see FIG. 2) showing the relationship between the pump
rotation speed N and the pressure P2 in the second fluid pressure
chamber 24 of the pump device 100 at a certain target flow amount
and a map (see FIG. 3) showing the relationship between the
pressure P2 in the second fluid pressure chamber 24 and the applied
current I for the proportional solenoid 32 are stored in advance in
the controller 60. Here, the target flow amount is a predetermined
value of the flow amount required by the fluid pressure apparatus
50, and in FIG. 2, the target flow amount corresponds to the flow
amount discharged from the pump 1 at the pump rotation speed
Nm.
[0036] In the pump device 100, the flow amount returning from the
discharge channel 82 to the suction channel 81 is controlled by the
flow control valve 2, and thereby, control is performed such that
the flow amount of the working oil supplied to the fluid pressure
apparatus 50 from the pump 1 through the discharge channel 82
becomes the target flow amount. Specifically, the controller 60
refers to the maps shown in FIGS. 2 and 3 and adjusts the pressure
P2 in the second fluid pressure chamber 24 of the flow control
valve 2 by controlling the relief valve 30, thereby controlling the
flow amount returning from the discharge channel 82 to the suction
channel 81.
[0037] The map shown in FIG. 2 will be described. In the pump 1, as
the pump rotation speed N increases, the discharge flow amount also
increases in a manner proportional to the rotation speed.
Therefore, the controller 60 refers to the map shown in FIG. 2, and
when the pump rotation speed N is greater than the rotation speed
Nm that corresponds to the target flow amount, in order to increase
the returning flow amount from the discharge channel 82 in
accordance with the increase in the pump rotation speed N, the
controller 60 performs control such that the set pressure for the
pressure P2 in the second fluid pressure chamber 24 is decreased.
In addition, when the pump rotation speed N is less than or equal
to the rotation speed Nm, in order not to allow return of the
working oil that has been discharged from the pump 1 to the
discharge channel 82, the pressure P2 in the second fluid pressure
chamber 24 is controlled so as to be constant.
[0038] Next, the map shown in FIG. 3 will be described. As shown in
FIG. 3, the pressure P2 in the second fluid pressure chamber 24 and
the applied current I for the proportional solenoid 32 of the
relief valve 30 are in the proportional relationship. Specifically,
in order to increase the pressure P2 in the second fluid pressure
chamber 24, the applied current I for the proportional solenoid 32
is increased. By doing so, the relief pressure Pr of the relief
valve 30 is increased, and in turn, the pressure P2 in the second
fluid pressure chamber 24 is increased. In contrast, in order to
reduce the pressure P2 in the second fluid pressure chamber 24, the
applied current I for the proportional solenoid 32 is lowered. By
doing so, the relief pressure Pr of the relief valve 30 is
decreased, and in turn, the pressure P2 in the second fluid
pressure chamber 24 is decreased.
[0039] Next, operation of the pump device 100 will be
described.
[0040] The pump 1 is rotationally driven by a motive force from a
driving device, such as an engine (not shown), and thereby, the
working oil is sucked from the tank 4 through the suction channel
81 and the working oil is pressurized and discharged to the
discharge channel 82. The working oil discharged into the discharge
channel 82 is supplied to the fluid pressure apparatus 50.
[0041] The pump rotation speed N of the pump 1 is changed in
accordance with the rotation speed of the driving device. As the
pump rotation speed N is increased, the discharge flow amount of
the pump 1 is also increased in a manner proportional to the
rotation speed.
[0042] When the pump 1 is driven, the working oil is supplied to
the first fluid pressure chamber 23 from the discharge channel 82
through the first communicating passage 83. With such a
configuration, the equal amount of pressure acts on the first fluid
pressure chamber 23 and the discharge channel 82. In addition, the
working oil is supplied to the second fluid pressure chamber 24
from the discharge channel 82 through the second communicating
passage 84. As for the pressure in the second fluid pressure
chamber 24, when the pump rotation speed N is less than the
rotation speed Nm, because the discharge flow amount of the pump 1
does not reach the target flow amount, the pressure in the second
fluid pressure chamber 24 is not increased to the relief pressure
Pr of the relief valve 30. Thus, because the working oil is not
relieved from the relief valve 30, the pressure P2 in the second
fluid pressure chamber 24 becomes equal to the pressure in the
first fluid pressure chamber 23. In contrast, when the pump
rotation speed N is greater than or equal to the rotation speed Nm,
because the discharge flow amount of the pump 1 becomes greater
than or equal to the target flow amount, in order to return a part
of the discharge flow amount of the pump 1, the pressure P2 in the
second fluid pressure chamber 24 is controlled by the relief valve
30. Therefore, the pressure P2 in the second fluid pressure chamber
24 becomes equal to the relief pressure Pr of the relief valve
30.
[0043] In addition, when the pump 1 is driven, the pump rotation
speed N is input to the controller 60 from the pump-rotation-speed
detector 70. The controller 60 refers to the map shown in FIG. 2
and selects the pressure P2 in the second fluid pressure chamber 24
corresponding to the input pump rotation speed N.
[0044] In the following, a case in which the pump device 100 is
controlled with a medium-pressure characteristic B shown in FIG. 2
will be described. The medium-pressure characteristic B will be
described later.
[0045] When the pump rotation speed N is the rotation speed Na that
is less than or equal to the rotation speed Nm, the discharge flow
amount of the pump 1 does not reach the target flow amount required
by the fluid pressure apparatus 50. Therefore, as shown in the map
in FIG. 2, in order not to return the flow amount discharged by the
pump 1, the controller 60 selects the pressure Pd as the pressure
P2 in the second fluid pressure chamber 24. Next, the controller 60
refers to the map shown in FIG. 3 and selects the applied current
Id for the proportional solenoid 32 of the relief valve 30
corresponding to the pressure Pd. As described above, the
controller 60 sets the relief pressure Pr of the relief valve 30 to
the pressure Pd by applying the applied current Id to the
proportional solenoid 32 of the relief valve 30. When the relief
pressure Pr of the relief valve 30 is set to the pressure Pd,
because the relief valve 30 will not be released until the pressure
P2 in the second fluid pressure chamber 24 becomes the pressure Pd,
the pressure in the first fluid pressure chamber 23 becomes equal
to the pressure in the second fluid pressure chamber 24. Thus,
although the biasing force in the valve-opening direction by the
pressure in the first fluid pressure chamber 23 and the biasing
force in the valve-closing direction by the pressure in the second
fluid pressure chamber 24 are cancelled out, because the spool 21
is biased in the valve-closing direction by the biasing force
exerted by the return spring 22, the spool 21 of the flow control
valve 2 is not opened. Therefore, the working oil discharged by the
pump 1 will not be returned.
[0046] When the pump rotation speed N is increased and becomes the
rotation speed Nb that is greater than the rotation speed Nm,
because the discharge flow amount of the pump 1 is greater than the
flow amount required by the fluid pressure apparatus 50, the
excessive flow amount is caused.
[0047] At this time, the controller 60 refers to the map shown in
FIG. 2 and selects the pressure Pb as the pressure P2 in the second
fluid pressure chamber 24 corresponding to the rotation speed Nb.
In order to reduce the pressure P2 in the second fluid pressure
chamber 24 from the pressure Pd to the pressure Pb, the controller
60 refers to the map shown in FIG. 3 and lowers the applied current
I from the applied current Id for the proportional solenoid 32 of
the relief valve 30 corresponding to the pressure Pd to the applied
current Ib for the proportional solenoid 32 of the relief valve 30
corresponding to the pressure Pb. By doing so, the biasing force
exerted by the proportional solenoid 32 is decreased and the relief
pressure Pr is decreased. When the relief pressure Pr is decreased,
the working oil is discharged from the second fluid pressure
chamber 24 such that the pressure P2 in the second fluid pressure
chamber 24 becomes the relief pressure Pr, and thereby, the
pressure P2 in the second fluid pressure chamber 24 is decreased to
the pressure Pb. As described above, the biasing force biasing the
spool 21 of the flow control valve 2 in the valve-closing direction
is decreased by an amount corresponding to the reduction of the
pressure P2 in the second fluid pressure chamber 24 from the
pressure Pd to the pressure Pb.
[0048] By doing so, although the discharge flow amount is increased
due to the increase in the rotation speed of the pump 1 to the
rotation speed Nb, because the spool 21 of the flow control valve 2
is opened and the working oil in the discharge channel 82 (the
excessive flow amount) is returned to the suction channel 81
through the first fluid pressure chamber 23 and the drain passage
85, the flow amount of the working oil supplied to the fluid
pressure apparatus 50 from the pump 1 is kept constant (at the
target flow amount).
[0049] When the pump rotation speed N is further increased to the
rotation speed Nc, the flow amount discharged from the pump 1 to
the discharge channel 82 is increased even further. At this time,
as shown in FIGS. 2 and 3, in order to reduce the pressure P2 in a
second fluid pressure chamber 24 from the pressure Pb to the
pressure Pe corresponding to the rotation speed Nc, the controller
60 lowers the applied current I from the applied current Ib to the
applied current Ie. By doing so, the biasing force in the flow
control valve 2 in the valve-closing direction is further
decreased. Therefore, although the discharge flow amount is
increased due to the increase in the rotation speed of the pump 1
to the rotation speed Nc, because the amount of the working oil
returning from the discharge channel 82 to the suction channel 81
is also increased, the flow amount of the working oil supplied to
the fluid pressure apparatus 50 from the pump 1 is kept constant
(at the target flow amount).
[0050] In contrast, when, for example, the pump rotation speed N is
decreased from the rotation speed Nc to the rotation speed Nb
within a range in which the pump rotation speed is greater than the
predetermined rotation speed Nm, the flow amount discharged from
the pump 1 to the discharge channel 82 is decreased, and the
excessive flow amount is also decreased. At this time, in order to
increase the pressure P2 in the second fluid pressure chamber 24
from the pressure Pe corresponding to the rotation speed Nc to the
pressure Pb corresponding to the rotation speed Nb, the controller
60 refers to the maps shown in FIGS. 2 and 3 and increases the
applied current I for the proportional solenoid 32 of the relief
valve 30 from the applied current Ie to the applied current Ib,
thereby increasing the relief pressure Pr. As the relief pressure
Pr is increased, the pressure P2 in the second fluid pressure
chamber 24 is also increased accordingly. Therefore, the biasing
force biasing the spool 21 of the flow control valve 2 in the
valve-closing direction is increased in accordance with the amount
of increase in the pressure P2 in the second fluid pressure chamber
24.
[0051] Thus, although the discharge flow amount is decreased due to
the decrease in the rotation speed of the pump 1 to the rotation
speed Nb, because the amount of the working oil returning to the
suction channel 81 through the first fluid pressure chamber 23 is
also decreased, the flow amount of the working oil supplied to the
fluid pressure apparatus 50 from the pump 1 is kept constant (at
the target flow amount).
[0052] As described above, even when the discharge flow amount of
the pump 1 is changed due to the change in the pump rotation speed
N of the pump 1, the pump device 100 can keep the flow amount
supplied to the fluid pressure apparatus 50 constant. In addition,
by using the relief valve 30, it is possible to adjust the pressure
with a simple configuration.
[0053] When, for example, the pressure required by the fluid
pressure apparatus 50 is increased while the flow amount is
controlled so as to be constant (at the target flow amount), the
pressure in the discharge channel 82 is increased and the pressure
in the first fluid pressure chamber 23 is also increased through
the first communicating passage 83. Thus, the biasing force biasing
the spool 21 of the flow control valve 2 in the valve-opening
direction is increased and the spool 21 is moved in the
valve-opening direction. As the degree of opening of the spool 21
is increased, the returning flow amount returning to the suction
channel 81 through the first fluid pressure chamber 23 and the
drain passage 85 is increased, causing the flow amount through the
discharge channel 82 to be changed. Therefore, even when the
pressure is changed, in order to keep the flow amount constant, the
pump device 100 selects the characteristics of the relationship
between the pump rotation speed N and the pressure P2 in the second
fluid pressure chamber 24 in accordance with the pressure. The
specific description thereof is given below.
[0054] A signal for the pressure required by the fluid pressure
apparatus 50 is input to the controller 60.
[0055] As the signal for the pressure required by the fluid
pressure apparatus 50 is input to the controller 60, the controller
60 selects, from the map shown in FIG. 2 stored in advance, the
characteristics of the relationship between the pump rotation speed
N and the pressure P2 in the second fluid pressure chamber 24 in
accordance with the pressure required by the fluid pressure
apparatus 50.
[0056] For example, while the control is performed at the pump
rotation speed Nb with the medium-pressure characteristic B, when
the pressure required by the fluid pressure apparatus 50 is
increased, the controller 60 selects a high-pressure characteristic
A shown in FIG. 2. In other words, the set pressure for the
pressure P2 in the second fluid pressure chamber 24 is changed from
the pressure Pb with the medium-pressure characteristic B to the
pressure Pa with the high-pressure characteristic A. By doing so,
the biasing force biasing the spool 21 of the flow control valve 2
in the valve-closing direction is increased. Although the pressure
in the discharge channel 82 is increased when the pressure required
by the fluid pressure apparatus 50 is increased and the biasing
force biasing the spool 21 in the valve-opening direction is
increased due to the increase in the pressure in the first fluid
pressure chamber 23, the pressure P2 in the second fluid pressure
chamber 24 is correspondingly increased and the biasing force
biasing the spool 21 of the flow control valve 2 in the
valve-closing direction is increased. As described above, the
degree of opening of the spool 21 of the flow control valve 2 is
adjusted such that the returning flow amount does not change. Thus,
it is possible to keep the flow amount through the discharge
channel 82 of the pump 1 constant (at the target flow amount).
[0057] In addition, while the control is performed at the pump
rotation speed Nb with the medium-pressure characteristic B, when
the pressure required by the fluid pressure apparatus 50 is
decreased, the controller 60 selects a low-pressure characteristic
C shown in FIG. 2. In other words, the set pressure for the
pressure P2 in the second fluid pressure chamber 24 is changed from
the pressure Pb with the medium-pressure characteristic B to the
pressure Pc with the low-pressure characteristic C. By doing so,
the biasing force biasing the spool 21 of the flow control valve 2
in the valve-closing direction is decreased. Although the pressure
in the discharge channel 82 is decreased when the pressure required
by the fluid pressure apparatus 50 is decreased and the biasing
force biasing the spool 21 in the valve-opening direction is
decreased due to the decrease in the pressure in the first fluid
pressure chamber 23, the pressure P2 in the second fluid pressure
chamber 24 is correspondingly decreased and the biasing force
biasing the spool 21 in the valve-closing direction is decreased.
As described above, the degree of opening of the spool 21 of the
flow control valve 2 is adjusted such that the returning flow
amount does not change. Thus, it is possible to keep the flow
amount through the discharge channel 82 of the pump 1 constant (at
the target flow amount).
[0058] As described above, even when the pressure required by the
fluid pressure apparatus 50 is changed, the controller 60 selects
the characteristics of the relationship between the pump rotation
speed N and the pressure P2 in the second fluid pressure chamber 24
in accordance with the pressure and controls the pressure P2 in the
second fluid pressure chamber 24 on the basis of the selected
characteristic, and thereby, it is possible to keep the flow amount
through the discharge channel 82 of the pump 1 constant (at the
target flow amount).
[0059] Although FIG. 2 shows stepwise characteristics like the
high-pressure characteristic A, the medium-pressure characteristic
B, and the low-pressure characteristic C, in practice, the
characteristics are changed continuously between the high-pressure
characteristic A and the low-pressure characteristic C. Of course,
the characteristics may be changed in a stepwise manner. The
medium-pressure characteristic B shown in FIG. 2 is only a
conceptual illustration of a characteristic between the
high-pressure characteristic A and the low-pressure characteristic
C.
[0060] The above-mentioned embodiment is configured such that the
signal for the pressure required by the fluid pressure apparatus 50
is input to the controller 60. Instead of this configuration, a
pressure detector may be provided in the discharge channel 82, and
the signal from the pressure detector may be input to the
controller 60. As the signal is input from the pressure detector,
the controller 60 refers to the map shown in FIG. 2 and selects
appropriate characteristics of the relationship between the pump
rotation speed N and the pressure P2 in the second fluid pressure
chamber 24 in accordance with the pressure in the discharge channel
82 detected by the pressure detector. By doing so, it is possible
to control the pump device 100 as in the case in which the signal
for the pressure required by the fluid pressure apparatus 50 is
input to the controller 60.
[0061] In addition, the pump device 100 may be configured such that
a plurality of maps of the target flow amount shown in FIG. 2 may
be stored in the controller 60 for each of different target flow
amounts, and the controller 60 may appropriately select a map
corresponding to the target flow amount in accordance with an
instruction from the fluid pressure apparatus 50. In order to
create a map with a different target flow amount, the position of
the rotation speed Nm forming a break point of a graph may only be
shifted to the position of pump rotation speed corresponding to the
target flow amount.
[0062] According to the embodiment mentioned above, the advantages
described below are afforded.
[0063] While a restrictor is conventionally provided in a discharge
channel connecting a pump and a fluid pressure apparatus and a flow
control valve is controlled on the basis of the pressure difference
between the upstream side and the downstream side thereof, in this
embodiment, because the flow control valve 2 includes the pressure
regulator 3 that is provided in the second communicating passage 84
through which the discharge channel 82 is communicated with the
second fluid pressure chamber 24 and that adjusts the pressure in
the second fluid pressure chamber 24, it is possible to control the
flow amount of the working oil supplied to the fluid pressure
apparatus 50 from the pump 1 so as to be constant without providing
a restrictor in the discharge channel 82. Furthermore, because a
restrictor is not provided in the discharge channel 82, no pressure
loss is caused, and it is possible to reduce the torque for driving
the pump 1. In addition, it is possible to keep the flow amount
constant even when the pressure required by the fluid pressure
apparatus 50 is changed.
[0064] Although the pump device 100 performs a flow amount control
in accordance with the pressure required by the fluid pressure
apparatus 50 such that the flow amount of the working oil supplied
to the fluid pressure apparatus 50 from the pump 1 is kept
constant, if the fluid pressure apparatus 50 requires a pressure
control to keep the pressure constant, by storing a map shown in
FIG. 4 in the controller 60 in advance, it is possible to perform
the pressure control to keep the pressure constant without
performing the flow amount control. The specific description
thereof is given below.
[0065] FIG. 4 is a map showing the relationship between the
required pressure Pp for the pump 1 and the pressure P2 in the
second fluid pressure chamber 24.
[0066] A signal for the required pressure Pp required by the fluid
pressure apparatus 50 is input to the controller 60 from the fluid
pressure apparatus 50.
[0067] As the signal for the required pressure Pp required by the
fluid pressure apparatus 50 is input to the controller 60, the
controller 60 controls the flow control valve 2 such that the
pressure of the working oil supplied to the fluid pressure
apparatus 50 becomes the required pressure Pp. Specifically, the
controller 60 refers to the maps shown in FIGS. 4 and 3 stored in
advance and performs control such that the pressure of the working
oil supplied to the fluid pressure apparatus 50 becomes the
required pressure Pp required. The controller 60 performs this
control by controlling the relief valve 30, thereby adjusting the
pressure P2 in the second fluid pressure chamber 24 of the flow
control valve 2, and by controlling the biasing force in the
valve-closing direction in the flow control valve 2.
[0068] Next, the pressure control of the pump device 100 will be
described in detail.
[0069] When the pump device 100 performs the pressure control, the
flow control valve 2 functions as a pressure control valve.
[0070] When the pressure in the discharge channel 82 is increased
and becomes greater than or equal to the required pressure Pp
required by the fluid pressure apparatus 50, in order to also
increase the pressure in the first fluid pressure chamber 23, the
biasing force exerted in the valve-opening direction of the spool
21 is increased. Because the pressure P2 in the second fluid
pressure chamber 24 is controlled by the relief valve 30, the spool
21 is moved against the load exerted by the pressure P2 in the
second fluid pressure chamber 24 and the biasing force exerted by
the return spring 22. As the spool 21 is moved, the first fluid
pressure chamber 23 is communicated with the drain passage 85.
Thus, the working oil in the discharge channel 82 is returned to
the suction channel 81 through the first fluid pressure chamber 23
and the drain passage 85, and the pressure in the discharge channel
82 is decreased.
[0071] When the pressure in the discharge channel 82 is decreased
to the required pressure Pp required by the fluid pressure
apparatus 50, the load exerted by the pressure in the first fluid
pressure chamber 23 is balanced with the total load of the load
exerted by the pressure P2 in the second fluid pressure chamber 24
in the valve-closing direction of the spool 21 and the biasing
force exerted by the return spring 22, and the spool 21 is stopped
at the balanced position. Thus, the flow amount with which the
discharge pressure becomes the required pressure Pp is supplied to
the discharge channel 82. As described above, even when the
pressure in the discharge channel 82 is changed, it is possible to
supply the required pressure Pp required by the fluid pressure
apparatus 50 by adjusting the pressure in the discharge channel 82
by the flow control valve 2.
[0072] In addition, there is a case in which the required pressure
Pp required by the fluid pressure apparatus 50 is changed. For
example, when the signal for increasing the required pressure Pp
from the pressure PM to the pressure PH is input to the controller
60 from the fluid pressure apparatus 50, the controller 60 first
refers to the map shown in FIG. 4 and selects the pressure Ph in
the second fluid pressure chamber 24 corresponding to the pressure
PH. Next, the controller 60 refers to the map shown in FIG. 3 and
selects the applied current Ih for the proportional solenoid 32
such that the pressure P2 in the second fluid pressure chamber 24
becomes the pressure Ph. The relief pressure Pr is increased by
applying thus selected applied current Ih to the proportional
solenoid 32 of the relief valve 30.
[0073] In contrast, for example, when the signal for decreasing the
required pressure Pp from the pressure PM to the pressure PL is
input to the controller 60 from the fluid pressure apparatus 50,
the controller 60 first refers to the map shown in FIG. 4 and
selects the pressure P1 in the second fluid pressure chamber 24
corresponding to the pressure PL. Next, the controller 60 refers to
the map shown in FIG. 3 and selects the applied current I1 for the
proportional solenoid 32 such that the pressure P2 in the second
fluid pressure chamber 24 becomes the pressure P1. The relief
pressure Pr is decreased by applying thus selected applied current
I1 to the proportional solenoid 32 of the relief valve 30.
[0074] As described above, even when the required pressure Pp
required by the fluid pressure apparatus 50 is changed, it is
possible to control the pressure in the discharge channel 82 to the
required pressure Pp required by the fluid pressure apparatus 50 by
controlling the applied current I for the proportional solenoid 32
of the relief valve 30 in accordance with the required pressure Pp
to control the relief pressure Pr, thereby controlling the biasing
force in the valve-closing direction of the flow control valve
2.
[0075] The configurations, operations, and effects of the
embodiment according to the present invention will be collectively
described below.
[0076] The pump device 100 includes the pump 1, in which the
working oil is sucked and the working oil is pressurized and
discharged to the discharge channel 82, and the flow control valve
2 that returns a part of the working oil discharged from the pump 1
to the suction side (the suction channel 81), wherein the flow
control valve 2 includes the valve body (the spool 21), the first
fluid pressure chamber 23 that is provided so as to face against
the first-side end surface of the valve body (the spool 21) and
that is communicated with the discharge channel 82, the second
fluid pressure chamber 24 that is provided so as to face against
the second-side end surface of the valve body (the spool 21) and
that is communicated with the discharge channel 82, the biasing
member (the return spring 22) that is accommodated in the second
fluid pressure chamber 24 in a compressed state for biasing the
valve body (the spool 21) in the valve-closing direction, and the
pressure regulator 3 that is provided in the second communicating
passage 84 through which the discharge channel 82 is communicated
with the second fluid pressure chamber 24 and that adjusts the
pressure P2 in the second fluid pressure chamber 24.
[0077] With this configuration, the pressure P2 in the second fluid
pressure chamber 24 of the flow control valve 2 is adjusted by the
pressure regulator 3. The flow control valve 2 is controlled so as
to be opened/closed in accordance with the pressure difference
between the first fluid pressure chamber 23 into which the pressure
in the discharge channel 82 is guided and the second fluid pressure
chamber 24 into which the pressure Pr that has been adjusted by the
pressure regulator 3 is guided. Therefore, it is possible to
control the flow amount through the discharge channel of the pump 1
so as to be constant without providing a restrictor in the
discharge channel 82. In addition, because a restrictor is not
provided in the discharge channel 82, it is possible to reduce the
torque for driving the pump 1.
[0078] In addition, the pump device 100 is characterized in that
the pressure regulator 3 includes the orifice 40 that is provided
in the second communicating passage 84 and the relief valve 30 that
is provided in the relief passage 86, which is branched off from
the second communicating passage 84 at the downstream side of the
orifice 40, and that is capable of changing the relief pressure
Pr.
[0079] In addition, the pump device 100 is characterized in that
the relief valve 30 includes the proportional solenoid 32 that is
capable of changing the relief pressure Pr.
[0080] With such a configuration, the pressure P2 in the second
fluid pressure chamber 24 is adjusted by the relief valve 30.
Therefore, by using the relief valve 30, it is possible to adjust
the pressure with a simple configuration.
[0081] In addition, the pump device 100 is characterized in that
the relief pressure Pr is adjusted by the relief valve 30 in
accordance with the pump rotation speed N of the pump 1.
[0082] With such a configuration, even when the pump rotation speed
N of the pump 1 is changed, by adjusting the relief pressure Pr in
accordance with the pump rotation speed N, it is possible to keep
the flow amount through the discharge channel 82 constant.
[0083] In addition, the pump device 100 is characterized in that
the relief valve 30 changes the relief pressure Pr in accordance
with the pressure required by the fluid pressure apparatus 50.
[0084] With such a configuration, even when the pressure required
by the fluid pressure apparatus 50 is changed, by controlling the
relief pressure Pr in accordance with the pressure required by the
fluid pressure apparatus 50, it is possible to keep the flow amount
through the discharge channel 82 constant.
[0085] The pump device 100 includes the flow control valve 2 and
the pressure regulator 3 that is provided in the second
communicating passage 84 through which the discharge channel 82 is
communicated with the second fluid pressure chamber 24 and that
adjusts the pressure in the second fluid pressure chamber 24, and
thereby, it is possible to keep the flow amount through the
discharge channel constant even when the pressure required by the
fluid pressure apparatus 50 is changed.
[0086] Embodiments of this invention were described above, but the
above embodiments are merely examples of applications of this
invention, and the technical scope of this invention is not limited
to the specific constitutions of the above embodiments.
[0087] In the above-mentioned embodiment, the pressure P2 in the
second fluid pressure chamber is changed in accordance with the
pump rotation speed N of the pump 1. Instead of this configuration,
a flow meter that detects the flow amount discharged by the pump 1
may be provided, and the pressure P2 in the second fluid pressure
chamber may be changed in accordance with the detected flow
amount.
[0088] In the above-mentioned embodiment, the pressure regulator 3
includes the relief valve 30 and the orifice 40. Instead of this
configuration, a configuration in which a three-way type
proportional solenoid control valve, which controls the
communication between the discharge channel 82 and the second fluid
pressure chamber 24 and controls the communication between the
second fluid pressure chamber 24 and the tank 4, is provided in the
second communicating passage 84 may be employed.
[0089] This application claims priority based on Japanese Patent
Application No. 2014-175449 filed with the Japan Patent Office on
Aug. 29, 2014, the entire contents of which are incorporated into
this specification.
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